Direct current (DC) to DC (DC-DC) converter circuits may be used in light emitting diode (LED) lighting systems to step down or up a voltage and provide a current to drive one or more LED devices or arrays. DC-DC converter circuits, such as buck converter circuits, boost converter circuits, and buck-boost converter circuits, may be operable in different modes by controlling an ON state and an OFF state of a switch coupled to the main inductor. Such modes may include, for example, a continuous current mode (CCM) in which the current through the main inductor never drops below zero during switching, a discontinuous current mode (DCM) during which current through the main inductor periodically drops to zero for a period of time before it begins flowing again, and a critical or boundary mode (CRM) in which the current through the main inductor periodically drops to zero and then instantly begins flowing again.